Biology · Transport in flowering plants. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
Transpiration is the loss of water vapour from leaves. Water evaporates from the wet surfaces of the mesophyll cells into the air spaces of the leaf. The vapour then diffuses out through the open stomata, from a high concentration inside the leaf to a lower one outside.
Anything that makes evaporation faster, or keeps the air outside the leaf dry, makes transpiration faster. If a plant loses water faster than its roots take it up, its cells lose water, become flaccid and the plant wilts.
Translocation is different. It is the movement of sucrose and amino acids in the phloem, from where they are made or stored (sources) to where they are used or stored (sinks).
Students write that water evaporates through the stomata. Water evaporates from the mesophyll cell surfaces inside the leaf; it is water vapour that diffuses out through the stomata.
Answer: 2.5 times faster, because wind keeps the water vapour gradient steep.
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